Caption: Cellular packaging of DNA. Artwork of a strand of the genetic material DNA (deoxyribonucleic acid) unwound from the nucleus (blue) of a cell (orange, upper right). The DNA in a cell nucleus (less than 0.1 millimetres across) is over 2 metres in length when unravelled. The double helix structure (lower right) is coiled around histone cores to form units known as nucleosomes (lower left). Further coiling produces fibres of chromatin (centre). Chromatin condenses to form structures known as chromosomes (one at upper right) during cell division.